1. Field of the Invention
Embodiments of the present invention relate to the fabrication of integrated circuits. More particularly, embodiments of the present invention relate to a process for depositing dielectric layers on a substrate.
2. Description of the Related Art
Integrated circuit geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore""s Law), which means that the number of devices on a chip doubles every two years. Today""s fabrication facilities are routinely producing devices having 0.13 xcexcm and even 0.1 xcexcm feature sizes, and tomorrow""s facilities will soon be producing devices having even smaller feature sizes.
The continued reduction in device geometries has generated a demand for films having lower k values because the capacitive coupling between adjacent metal lines must be reduced to further reduce the size of devices on integrated circuits. In particular, insulators having low dielectric constants (k), less than about 4.0, are desirable. Examples of insulators having low dielectric constants include spin-on glass, un-doped silicon glass (USG), fluorine-doped silicon glass (FSG), and polytetrafluoroethylene (PTFE), which are all commercially available.
An effective method to lower the k value is to introduce pores into the film. Consequently, however, low k films often have a low mechanical strength (e.g., hardness), which may hinder the integration of the films into the manufacture of the device. Electron beam post treatment is currently being used to increase the mechanical strength of low k films. One example of an electron beam apparatus used to treat low k films is a large-area electron source, which includes an anode that is typically made from graphite. It has recently been observed, however, that graphite anodes tend to bow or break in response to varying temperatures during treatment, which may result in particle contamination on the films.
Therefore, a need exists for a method and apparatus of an improved electron beam apparatus for treating low k films.
Embodiments of the present invention are generally directed to an electron beam apparatus. In one embodiment, the electron beam apparatus includes a vacuum chamber, a large-area cathode disposed in the vacuum chamber, and a first power supply connected to the cathode. The first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber. The electron beam apparatus further includes an anode positioned between the large-area cathode and the substrate. The anode is made from aluminum. The electron beam apparatus further includes a second power supply connected to the anode, wherein the second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode.
In another embodiment of the invention, the electron beam apparatus includes a vacuum chamber in which an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. The electron beam apparatus further includes a large-area cathode disposed in the vacuum chamber, a first power supply connected to the cathode. The first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber. The electron beam apparatus further includes an anode positioned between the large-area cathode and the substrate, and a second power supply connected to the anode. The second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode.
In yet another embodiment of the invention, the electron beam apparatus includes a vacuum chamber, a large-area cathode disposed in the vacuum chamber, and a first power supply connected to the cathode. The first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber. The electron beam chamber further includes an anode placed between the large-area cathode and the substrate, and a shelf disposed in the vacuum chamber. The shelf defines a surface on which the anode is placed. The electron beam chamber further includes a second power supply connected to the anode. The second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode.